A. Technical Field
This invention generally relates to network switching devices and more particularly to Fibre Channel switching devices.
B. Background of the Invention
As the result of continuous advances in technology, particularly in the area of networking such as the Internet, there is an increasing demand for communications bandwidth. For example, the transmission of data over a telephone company's trunk lines, the transmission of images or video over the Internet, the transfer of large amounts of data as might be required in transaction processing, or videoconferencing implemented over a public telephone network typically require the high speed transmission of large amounts of data. Such applications create a need for data centers to be able to quickly provide their servers with large amounts of data from data storage. As such data transfer needs become more prevalent, the demand for high bandwidth and large capacity in data storage will only increase.
Fibre Channel is a transmission medium that is well-suited to meet this increasing demand, and the Fibre Channel family of standards (developed by the American National Standards Institute (ANSI)) is one example of a standard which defines a high speed communications interface for the transfer of large amounts of data via connections between a variety of hardware devices, including devices such as personal computers, workstations, mainframes, supercomputers, and storage devices. The Fibre Channel family of standards includes FC-PH (ANSI X3.230-1994), FC-PH-Amendment 1 (ANSI X3.230-1994/AM 1-1996), FC-PH-2 (ANSI X3.297-1997), FC-PH-3 (ANSI X3.303-1998), FC-SW (ANSI NCITS 321-1998), and FC-FG (ANSI X3.289-1996), which are fully incorporated by reference. Use of Fibre Channel is proliferating in many applications, particularly client/server applications that demand high bandwidth and low latency I/O. Examples of such applications include mass storage, medical and scientific imaging, multimedia communications, transaction processing, distributed computing and distributed database processing applications.
In one aspect of the Fibre Channel standard, communication between devices occurs through one or more Fibre Channel switches. With Fibre Channel switches having large port counts, large amounts of data can pass through the switch and congestion can result. If congestion occurs within the Fibre Channel switch, communication slows and performance suffers.
Accordingly it is desirable to provide a large port count switch with little congestion.